Yea this game is notorious stingy with the H scenes.
There is a japanese walkthrough
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From what I mange to fathom my theory is you need to start the game and get the first park peep scene. You can get park peep scenes by talking to the gossipers when they have something to talk and going to the park to the north and on the right part where it is seemingly empty.
The peep scene changes as you continue the story so you need the first.
After that you raise the slut meter through battle rape GoR for the normal enemies by ripping the cloths(until naked and grouped) and the boss(2 enemies), after that the H scene with the flower boss. After that the masturbation scene.
That would theoretically seduce the first park peep scene guy.I don't know for sure since I missed it in my playthrough.
I would love a save with him unlocked.